Capacitance multiplier (CB7803E)

We found this circuit in an old Popular Electronics. The circuit can be applied to other operational amplifiers.

5 W Amplifier with Germanium Transistors (CB14765E)
This experimental amplifier was found in the 1960 Mullard transistor reference manual. The...
Light-operated relay (CB8285E)
This circuit from Motorola is from 1968, appearing elsewhere on this site. The transistors admit...
Battery Low Indicator (CB4796E)
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...